For example, I wanted to use a Class 76 as the player engine, but quickly discovered that the majority of the Wath yard tracks are not electrified. This surprised me, but I simply switched engines, selecting instead the Class 08 that also came with the route. And this engine, combined with the route's track, especially turnouts, had been the source of numerous frustrations. Why? Simply because it causes scenario-ending "consist tilt" errors seemingly at random not only while crossing turnouts at anything above 9 mph, but also on absolutely straight stretches of track, and even while standing absolutely still.
As is my habit (or vice, perhaps), I've added a good deal of AI traffic, and that has also been problematic, not so much for the usual reason of mistaken editing on my part, but more due to random AI collisions. By random, I mean that they occur during one run-through of the scenario but not in the next without my having made any changes to their instructions.
Then there have been problems associated with what I can only call faulty rolling stock. Woodhead comes with the aforementioned Class 76 and 08 engines, a steam engine that has performed admirably, some passenger carriages, and several freight wagons. As I have noted in another thread, the Class 76 engine's lights are on even when it is placed as a stationary, driver-less unit, which not only looks ridiculous, but also creates a serious FPS drain. Some of the coal and mineral hoppers cannot be used actively in scenarios without assigning each one a new number; if this is not done, they cannot be picked up or dropped off successfully by a player train and cause crashes with a shunting AI train. Finally, the Brake Wagon is also "always on": its red tail marker glows and its stovepipe smokes even when it is not part of a running train.
Despite all of these impediments to success, I finally managed to run the scenario from beginning to end today (well, yes, with several restarts due to Class 08 consist tilt errors). Will this ever happen again? I honestly cannot say, but here are a few screenshots from this work in progress:





Coming soon to an RW3 installation near you ... maybe? ... I hope!